title: A unique iron-sulfur cluster is crucial for oxygen tolerance of a [NiFe]-hydrogenase.
abstract: Hydrogenases are essential for H(2) cycling in microbial metabolism and serve as valuable blueprints for H(2)-based biotechnological applications. However, most hydrogenases are extremely oxygen sensitive and prone to inactivation by even traces of O(2). The O(2)-tolerant membrane-bound [NiFe]-hydrogenase of Ralstonia eutropha H16 is one of the few examples that can perform H(2) uptake in the presence of ambient O(2). Here we show that O(2) tolerance is crucially related to a modification of the internal electron-transfer chain. The iron-sulfur cluster proximal to the active site is surrounded by six instead of four conserved coordinating cysteines. Removal of the two additional cysteines alters the electronic structure of the proximal iron-sulfur cluster and renders the catalytic activity sensitive to O(2) as shown by physiological, biochemical, spectroscopic and electrochemical studies. The data indicate that the mechanism of O(2) tolerance relies on the reductive removal of oxygenic species guided by the unique architecture of the electron relay rather than a restricted access of O(2) to the active site.
authors.affiliation: Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Goris
authors.forename: Annemarie F
authors.initials: AF
authors.lastname: Wait
authors.forename: Miguel
authors.initials: M
authors.lastname: Saggu
authors.forename: Johannes
authors.initials: J
authors.lastname: Fritsch
authors.forename: Nina
authors.initials: N
authors.lastname: Heidary
authors.forename: Matthias
authors.initials: M
authors.lastname: Stein
authors.forename: Ingo
authors.initials: I
authors.lastname: Zebger
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Lendzian
authors.forename: Fraser A
authors.initials: FA
authors.lastname: Armstrong
authors.forename: Bärbel
authors.initials: B
authors.lastname: Friedrich
authors.forename: Oliver
authors.initials: O
authors.lastname: Lenz
mesh_terms: D055162:Biocatalysis; D002245:Carbon Dioxide / Q000737:chemistry / Q000378:metabolism; D020134:Catalytic Domain; D020118:Cupriavidus necator / Q000201:enzymology / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D004563:Electrochemistry; D004591:Electrophoresis, Polyacrylamide Gel; D006859:Hydrogen / Q000737:chemistry / Q000378:metabolism; D006864:Hydrogenase / Q000737:chemistry / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism*; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D007506:Iron-Sulfur Proteins; D002245:Carbon Dioxide; D006859:Hydrogen; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; D003545:Cysteine; D010100:Oxygen